diff --git a/compiler/ccgstmts.nim b/compiler/ccgstmts.nim
index 83f5e90172..bc9c06fa1d 100644
--- a/compiler/ccgstmts.nim
+++ b/compiler/ccgstmts.nim
@@ -1237,6 +1237,7 @@ proc genTryCpp(p: BProc, t: PNode, d: var TLoc) =
         else:
           scope = initScope(p.s(cpsStmts))
       # we handled the error:
+      linefmt(p, cpsStmts, "T$1_ = nullptr;$n", [etmp])
       expr(p, t[i][0], d)
       linefmt(p, cpsStmts, "#popCurrentException();$n", [])
       endBlockWith(p):
diff --git a/compiler/guards.nim b/compiler/guards.nim
index 553cc744df..fcfafc954a 100644
--- a/compiler/guards.nim
+++ b/compiler/guards.nim
@@ -46,7 +46,7 @@ proc isLocation(n: PNode): bool = not n.isValue
 
 proc isLet(n: PNode): bool =
   if n.kind == nkSym:
-    if n.sym.kind in {skLet, skTemp, skForVar}:
+    if n.sym.kind in {skLet, skConst, skTemp, skForVar}: # guard immutable variables
       result = true
     elif n.sym.kind == skParam and skipTypes(n.sym.typ,
                                              abstractInst).kind notin {tyVar}:
diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim
index 9c84b721ad..f1e2e69cbe 100644
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -1208,6 +1208,7 @@ type
     enforcedGcSafety, enforceNoSideEffects: bool
     oldExc, oldTags, oldForbids: int
     exc, tags, forbids: PNode
+    excSource, tagsSource, forbidsSource: PNode
 
 proc createBlockContext(tracked: PEffects): PragmaBlockContext =
   var oldForbidsLen = 0
@@ -1230,17 +1231,18 @@ proc unapplyBlockContext(tracked: PEffects; bc: PragmaBlockContext) =
     # anything about 'raises' in the 'cast' at all. Same applies for 'tags'.
     setLen(tracked.exc.sons, bc.oldExc)
     for e in bc.exc:
-      addRaiseEffect(tracked, e, e)
+      addRaiseEffect(tracked, e, if bc.excSource != nil: bc.excSource else: e)
   if bc.tags != nil:
     setLen(tracked.tags.sons, bc.oldTags)
     for t in bc.tags:
-      addTag(tracked, t, t)
+      addTag(tracked, t, if bc.tagsSource != nil: bc.tagsSource else: t)
   if bc.forbids != nil:
     setLen(tracked.forbids.sons, bc.oldForbids)
     for t in bc.forbids:
-      addNotTag(tracked, t, t)
+      addNotTag(tracked, t, if bc.forbidsSource != nil: bc.forbidsSource else: t)
 
-proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
+proc castBlock(tracked: PEffects, castPragma: PNode, bc: var PragmaBlockContext) =
+  let pragma = castPragma[1]
   case whichPragma(pragma)
   of wGcSafe:
     bc.enforcedGcSafety = true
@@ -1253,6 +1255,7 @@ proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
     else:
       bc.tags = newNodeI(nkArgList, pragma.info)
       bc.tags.add n
+    bc.tagsSource = castPragma
   of wForbids:
     let n = pragma[1]
     if n.kind in {nkCurly, nkBracket}:
@@ -1260,6 +1263,7 @@ proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
     else:
       bc.forbids = newNodeI(nkArgList, pragma.info)
       bc.forbids.add n
+    bc.forbidsSource = castPragma
   of wRaises:
     let n = pragma[1]
     if n.kind in {nkCurly, nkBracket}:
@@ -1267,6 +1271,7 @@ proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
     else:
       bc.exc = newNodeI(nkArgList, pragma.info)
       bc.exc.add n
+    bc.excSource = castPragma
   of wUncheckedAssign:
     discard "handled in sempass1"
   else:
@@ -1520,7 +1525,7 @@ proc track(tracked: PEffects, n: PNode) =
       of wNoSideEffect:
         bc.enforceNoSideEffects = true
       of wCast:
-        castBlock(tracked, pragmaList[i][1], bc)
+        castBlock(tracked, pragmaList[i], bc)
       else:
         discard
     applyBlockContext(tracked, bc)
diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index bf9c2d2050..dd5944899b 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -791,8 +791,10 @@ proc procParamTypeRel(c: var TCandidate; f, a: PType): TTypeRelation =
     # different C types (size_t vs unsigned long long).
     let fCheck = concreteType(c, f)
     let aCheck = concreteType(c, a)
+    # Note that `result` is equal; now check whether they have the same
+    # backend type.
     if fCheck != nil and aCheck != nil and
-        not sameBackendTypePickyAliases(fCheck, aCheck):
+      not sameBackendTypePickyAliases(fCheck, aCheck, {IgnoreFlags}):
       result = isNone
 
   if result <= isSubrange or inconsistentVarTypes(f, a):
@@ -2471,6 +2473,10 @@ proc paramTypesMatchAux(m: var TCandidate, f, a: PType,
       return arg
     elif f.kind == tyStatic and arg.typ.n != nil:
       return arg.typ.n
+    elif f.kind == tyUntyped:
+      # bug #25693: a different overload candidate may have sem-checked the
+      # operand and left symbols behind; templates expect the pristine AST.
+      return argOrig
     else:
       return argSemantized # argOrig
 
diff --git a/compiler/types.nim b/compiler/types.nim
index de24471e7d..f4c7e74bc5 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1069,9 +1069,10 @@ proc sameBackendTypeIgnoreRange*(x, y: PType): bool =
   c.cmp = dcEqIgnoreDistinct
   result = sameTypeAux(x, y, c)
 
-proc sameBackendTypePickyAliases*(x, y: PType): bool =
+proc sameBackendTypePickyAliases*(x, y: PType, flags: TTypeCmpFlags = {}): bool =
   var c = initSameTypeClosure()
   c.flags.incl {IgnoreTupleFields, IgnoreRangeShallow, PickyCAliases, PickyBackendAliases}
+  c.flags.incl flags
   c.cmp = dcEqIgnoreDistinct
   result = sameTypeAux(x, y, c)
 
diff --git a/lib/pure/parsejson.nim b/lib/pure/parsejson.nim
index 9292a85964..657f8cc697 100644
--- a/lib/pure/parsejson.nim
+++ b/lib/pure/parsejson.nim
@@ -175,23 +175,48 @@ proc parseEscapedUTF16*(buf: cstring, pos: var int): int =
     else:
       return -1
 
+proc addSpan(dst: var string; src: string; startPos, endPos: int) {.inline.} =
+  let n = endPos - startPos
+  if n <= 0:
+    return
+
+  let old = dst.len
+  dst.setLen old + n
+
+  template impl =
+    for i in 0..<n:
+      dst[old + i] = src[startPos + i]
+
+  when nimvm:
+    impl
+  else:
+    when defined(js) or defined(nimscript):
+      impl
+    else:
+      {.noSideEffect.}:
+        copyMem dst[old].addr, src[startPos].unsafeAddr, n
+
 proc parseString(my: var JsonParser): TokKind =
   result = tkString
   var pos = my.bufpos + 1
+  var spanStart = pos
   if my.rawStringLiterals:
     add(my.a, '"')
   while true:
     case my.buf[pos]
     of '\0':
-      my.err = errQuoteExpected
+      my.err = errInvalidToken
+      addSpan(my.a, my.buf, spanStart, pos)
       result = tkError
       break
     of '"':
+      addSpan(my.a, my.buf, spanStart, pos)
       if my.rawStringLiterals:
         add(my.a, '"')
       inc(pos)
       break
     of '\\':
+      addSpan(my.a, my.buf, spanStart, pos)
       if my.rawStringLiterals:
         add(my.a, '\\')
       case my.buf[pos+1]
@@ -251,14 +276,18 @@ proc parseString(my: var JsonParser): TokKind =
         # don't bother with the error
         add(my.a, my.buf[pos])
         inc(pos)
+      spanStart = pos
     of '\c':
+      addSpan(my.a, my.buf, spanStart, pos)
       pos = lexbase.handleCR(my, pos)
       add(my.a, '\c')
+      spanStart = pos
     of '\L':
+      addSpan(my.a, my.buf, spanStart, pos)
       pos = lexbase.handleLF(my, pos)
       add(my.a, '\L')
+      spanStart = pos
     else:
-      add(my.a, my.buf[pos])
       inc(pos)
   my.bufpos = pos # store back
 
diff --git a/tests/effects/tcast_effect_violation.nim b/tests/effects/tcast_effect_violation.nim
new file mode 100644
index 0000000000..fe7f93cc4a
--- /dev/null
+++ b/tests/effects/tcast_effect_violation.nim
@@ -0,0 +1,8 @@
+discard """
+  errormsg: "cast(raises: ValueError) can raise an unlisted exception: ValueError"
+  line: 7
+"""
+
+proc fff() {.raises: [].} =
+  {.cast(raises: ValueError).}:
+    discard
\ No newline at end of file
diff --git a/tests/exception/treraise_typeless_except_finally.nim b/tests/exception/treraise_typeless_except_finally.nim
new file mode 100644
index 0000000000..259863e4d4
--- /dev/null
+++ b/tests/exception/treraise_typeless_except_finally.nim
@@ -0,0 +1,30 @@
+discard """
+  targets: "cpp"
+  matrix: "--mm:arc; --mm:orc; --mm:refc"
+  output: '''
+finally
+after
+'''
+"""
+
+# Regression test: typeless `except:` followed by `finally:` must not
+# trigger ReraiseDefect at the end of the proc.
+#
+# Previously, `genTryCpp` only emitted `T_ = nullptr;` in the *typed*
+# except branches, leaving the typeless `except:` path with a still-set
+# `T_`.  After the handler body and `popCurrentException`, the trailing
+# `if (T_) std::rethrow_exception(T_);` in the finally block would still
+# fire — but with the Nim exception stack already popped, the rethrow
+# bubbled up as a `ReraiseDefect: no exception to reraise`.
+
+proc test() =
+  try:
+    raise newException(CatchableError, "x")
+  except:
+    let e = getCurrentException()
+    discard e
+  finally:
+    echo "finally"
+
+test()
+echo "after"
diff --git a/tests/objvariant/tcorrectcheckedfield.nim b/tests/objvariant/tcorrectcheckedfield.nim
index e5e67c727d..acb3acda14 100644
--- a/tests/objvariant/tcorrectcheckedfield.nim
+++ b/tests/objvariant/tcorrectcheckedfield.nim
@@ -20,3 +20,25 @@ block: # issue #24021
       discard
     else:
       discard foo.z
+
+
+# bug #22791
+type Foo = object
+  case a: bool
+  of false:
+    discard
+  of true:
+    case b: bool
+    of false:
+      discard
+    of true:
+      c: bool
+
+const f = Foo(a: true, b: true, c: true)
+case f.a
+of true:
+  case f.b
+  of true:
+    echo f.c
+  else: discard
+else: discard
\ No newline at end of file
diff --git a/tests/proc/tproc.nim b/tests/proc/tproc.nim
index d7f8619917..564f9be31b 100644
--- a/tests/proc/tproc.nim
+++ b/tests/proc/tproc.nim
@@ -29,3 +29,30 @@ block tnestprc:
       result = x + y
     result = add(x, 3)
   doAssert Add3(7) == 10
+
+block:
+  type A = object
+    c: int
+  type H = proc(): lent A {.nimcall.}
+  const u = A(c: 0)
+  proc e(T: typedesc): lent A = u
+  proc y(T: typedesc): H =
+    proc(): lent A {.nimcall.} = T.e
+  discard y(int)
+
+block:
+  type A = object
+    c: int
+  type H = proc(): lent A {.nimcall.}
+  let u = A(c: 0)
+  proc y(_: int | int): H =
+    proc(): lent A {.nimcall.} = u
+  discard y(0)
+
+block:
+  type A = object
+    c: int
+  type H = proc(): lent A {.nimcall.}
+  let u = A()
+  let _: H = proc(): lent A {.nimcall.} = u
+
diff --git a/tests/template/toverload_over_untyped.nim b/tests/template/toverload_over_untyped.nim
new file mode 100644
index 0000000000..0f734480d6
--- /dev/null
+++ b/tests/template/toverload_over_untyped.nim
@@ -0,0 +1,32 @@
+discard """
+  output: "ok"
+"""
+
+# bug #25693
+
+template g(b: untyped) {.dirty.} =
+  template t: untyped = b
+
+proc d() = discard @[0]
+proc g(_: int) = discard
+
+proc f(a: var seq[int], _: string) =
+  let p = @[0]
+  d()
+  a = p
+
+let q = "a"
+g:
+  var a: seq[int]
+  try:
+    f(a, q & "1")
+  except CatchableError:
+    discard
+  try:
+    f(a, q & "1")
+  except CatchableError:
+    discard
+block: t()
+block: t()
+echo "ok"
+